[en] Tree different wet chemical methods namely, flame hydrolysis, polymeric routes and sol-gel were developed and applied in this study for the production of very pure, fine and homogeneous ceramic powders. Physico-chemical properties for the produced powders using these techniques were investigated and discussed.The effect of preparation methods, calcination temperature on the specific total surface area, morphology, phase transformation and axial shrinkage of the fabricated powder were studied. Also the effect of preparation methods, calcination temperature for the pressed powder (compact samples) on the density of the sintered samples were studied and discussed. This comparative study permitted the selection and optimization of the most suitable method to fabricate an ultra fine powders which produce high dense compact materials suitable for industrial, biological and nuclear applications

[en] In an attempt to remove radioactive (¹⁵²+¹⁵⁴)Eu from waste solutions, the present study was tried to explore the possibility of using a natural by-product. Almond endocarp (AEC) shell produced from Sinai (El-Arish area) was selected as agricultural by-product in treatment of waste solutions containing (¹⁵²+¹⁵⁴)Eu through a batch technique. The different physico-chemical characteristics of AEC such as specific surface area, total pore volume, average pore diameter, apparent density, porosity and pore size distribution were calculated. The adsorption process was described by a Freundlich type isotherm. The uptake percent of the metal ion was determined for the sorbent material as a function of contact time, pH-value, mass of the sorbent material, metal ion concentration and the effect of competing ions on the sorption process. The obtained data were analyzed and showed that almond endocarp shell powder can be considered as an efficient natural material to be used for sorption of radioactive (¹⁵²+¹⁵⁴)Eu from their radioactive waste solutions

[en] Binary nano-ceramic materials, namely aluminium oxide/silicon oxide, zirconium oxide / Aluminium oxide and zirconium oxide / silicon oxide was prepared applying the sol-gel technique. powder processing using metal alkoxides as precursors for metal oxides was described. the morphology of the produced powders was experimentally characterized using scanning electron microscope, while the specific surface area was followed using BET - apparatus. the pore size distribution of the prepared binary nano-ceramic powders using a mercury porosimeter was measured. the thermal behavior was examined with the aid of DTA-T G analysis. in addition , the axial shrinkage of the prepared materials was followed using a heating microscope. the effect of temperature on the density of the studied materials permitted calculations of their relative percent theoretical density and study of their densification behavior . the experimental results of the physico-chemical characteristics for the prepared dried binary powders led to fine morphology, homogeneous grain size distribution, and high degree of compaction and high density. The fore mentioned characteristics are suitable for the decontamination of the radioactive waste

[en] Cylindrical powder compacts were prepared by uni-axial pressing of industrial T.V. waste glass. The anisotropic behavior was followed under isothermal conditions through the densification behavior of the products using a heating microscope. The samples became nearly fully dense at a temperature of about 650 degree in few minutes and showed an anisotropic shrinkage during densification. At the earlier stages of sintering the radial shrinkage was higher than the axial shrinkage, while this behavior was reversed at the later sintering stages. Explanation of this behavior was discussed on the basis of the phases formed for the samples during the sintering process. Experimental values for the shrinkage behavior in the radial direction were calculated and found to be in agreement with the theoretical values given in the literature. shielding bricks were prepared from TV glass waste in addition to another three different local industrial solid wastes, namely Jasin glass, arc furnace slag and fly ash, by mixing with cross linked poly bis phenol-epichlorohydrin resin. The products found applications as radioactive shielding bricks against 834.0 KeV for Mn-54, 1115.0 KeV for Zn-65, 301.7 KeV for Sn-113, 661.6 KeV for Cs-137 and 122.1 KeV for Co-57 sources

[en] Okra is an essential vegetable world over, but in past decade, a reduction in per hectare yield was noted. Amongst various reasons for its low yield, weeds are the most important. These weeds reduce the crop growth by competing for resources and by allelopathic effects. During surveys of okra fields in Pakistan, amongst others, Trianthema portulacastrum L. and Parthenium hysterophorus L. were noted but no data till to date are available that show comparative allelopathic potential of these weeds in okra. So, in the recent investigation, experiments were executed to assess the allelopathic effects of these two weeds on okra. Soil amendment with T. portulacastrum significantly reduced the shoot length of okra up to 42%, root length up to 73%, shoot dry weight up to 84%, root dry weight up to 73% and chlorophyll a up to 48%, chlorophyll b up to 50% and carotenoid up to 19.5%. Similar inhibitory effects were observed in case of P. hysterophorus but with comparatively less intensity. Gas Chromatography Mass Spectrometry analysis of T. portulacastrum revealed the presence of compounds viz., Phytol, 11-octadecenoic acid, methyl ester, 8, 11-Octadecadienoic acid, metlyl ester and Pentadecanoic acid at the highest concentrations. While in case of P. hysterophorus, following compounds were present at the highest concentrations; Phorbol, 1, 2-Benzenedicarboxylic acid, mono (2-ethylhexyl) ester, Isolongifolene-7, 8-dehydro- 8a-hydroxy- and 1H-cycloprop[e]azulene, 1a, 2, 3, 4, 4a, 5, 6, 7b-octahydro-1, 1, 4, 7-tetramethyl-, [1ar (1a.alpha., -4.alpha., 4a.beta.,7b.alpha.)]-. It can be concluded that these compounds may be responsible for allelopathic effects observed during the present study. (author)

No abstract available

[en] The ion exchange behaviour of U(V I), Th(IV) and Ce(IV) on a system composed of AL₂ O₃-Si O₂-Ti O₂ mixed metal oxides was studied. The mixed metal oxide ternary system contains 5-50% Al₂ O₃, 0.85% Si O₂ and 7-80% Ti O₂, and it was prepared by hydrolysis, polymerization and poly condensation of the corresponding metal alkoxides in presence of alcohol and bidistilled water. The composition of the examined system was followed using X-ray fluorescence, while the DTA and TGA indicated both phase transfer and weight loss of the system during heat treatment. The uptake of U(V I), Th(IV) and Ce(IV) species on the different samples representing the ternary mixed metal oxide systems was carried out from different media. In the absence of complexing agents, the studies were carried out at low PH-values to avoid hydrolysis of Th(IV) and Ce(IV) species in aqueous solutions. The exchange behaviour of the mentioned elements species was also studied at higher PH-values in the presence of ammonium carbonate, as complexing agent. The effect of the organic acids oxalic and citric, as complexing agents, on the exchange behaviour also studied. From the different uptake studies of the U(V I), Th(V I), and Ce(IV) species from different media at different PH-values, some concentration and separation alternatives for these metal species were recommended

[en] Alumina, titania and silica were prepared by an advanced wet chemical method, namely sol-gel process. Characterization of the obtained gel derived metal oxide powders, through their powder morphology using a scanning electron microscope (SEM), BET surface area measurements, simultaneous DTA and TG measurements, and X-ray diffraction analysis were performed. These measurements proved that the gel derived metal oxide powders produced by hydrolysis of metal alkoxides are of a very high reactivity, homogeneity, and fine particle size. The uptake behavior of the fabricated sol-gel powders for radioactive Eu (III) was studied. The experimental results showed that Eu (III) uptake on the prepared ceramic powders were of the order titania > alumina> silica. In addition the stability of these ceramic powders for Eu (III) uptake was examined through a desorption process of the adsorbed ions by distilled water. The desorption process proved also the stability of the materials used for Eu (III) uptake. 12 figs., 2 tabs

[en] The angular distribution of the transferred spin polarization of Kr M_4,5N₁N_2,3¹P₁ Auger electrons after primary ionization with circularly polarized light has been measured and the intrinsic parameters δ₁ and ξ₁ have been determined from experimental results. The explicit equation interconnecting the intrinsic parameters for Auger decay from a (d_5/2)^-1 core hole has been derived and is used for a detailed analysis of the transitions in terms of Auger amplitude ratios and phase shift differences. The results indicate that the final ionic state is well described by a ¹P symmetry. Additional constraints imposed on the intrinsic parameters for singlet states prevent unambiguous determination of Auger amplitudes from experiment even in the limiting case of pure LS coupling. (author)

[en] The uptake of Eu(III) and Zr(IV) was studied on ceramic materials of Ti O₂, Si O₂ and Al₂ O₃, prepared by the hydrolysis process. The uptake behaviour of Eu(III) and Zr(IV) was investigated under different experimental conditions such as contact time, PH-value in the presence and in absence of complexing agent. X-ray fluorescence, powder morphology, specific surface area, X-ray diffraction analysis in addition to the DTA and TGA were applied on the tested ceramic samples. The present study showed that the ceramic materials, prepared by an advanced technique are not only efficient for uptake of Eu(III) and Zr(IV), but also permitted the separation of these radioisotopes. 8 figs., 1 tab